Very many things doctors need to be aware of, because the patients life depends on it, are left out when patients move between specialists and physicians, which happens all of the time.
Outbreaks of viral and bacterial illnesses result in thousands of people independently chasing diagnoses and treatment, because the system doesn't share information that could be used to piece together and get ahead of it. Every time my kid gets sick at school, I get to play a game of "What is it? Do we see a Doctor? How much money should we spend?". Lets pretend we know nothing about this and go see a Doctor who hasn't seen anyone else in school, who may provide antibiotics they may or may not need or worse.
Effective prevention methods and early detection of bad treatment are discarded because its so difficult to investigate and connect the dots between interventions and outcomes.
Patient privacy is important, but the system we have today is nothing less than a tragedy. Real damage in emotional, physical, and economic is happening on a grand scale every day in this country. We shouldn't pretend HIPPA is a good thing, or the current system is doing a good job. Its not. We need to radically transform how we operate, and much more open and connected medical records is certainly a part of that transformation.